Godot: Dialog text is not copyable

[safield]

Godot: 3.1.1

The text in certain dialogs can not be selected and copied.

For example on an error dialog popup, the text is not selectable or copyable, which is the standard expected behaviour.

Another example would be the about popup dialog where the version number is not copyable.

[Zylann]

Either we should put a "copy text" button/shortcut available on every popup, or we add text selectability to labels (which we could then be used in other places such as script editor errors).
Or use a RichTextLabel which I think is selectable? (since it's used in docs)

[Calinou]

@Zylann It could be a good idea to make all dialogs use a RichTextLabel, as this also makes it possible to use BBCode formatting. I'm not sure if #18260 would block this though.